Spark-plhg



Patented June 3, 1919.

III. .i i 421 45 /////4v47//////z v wuewtoz Ea q C 4/07 119 it} M LAROYC. MONISMITH, F GLENVIL, NEBRASKA.

SPARK-PLUG.

Specification of Letters Patent.

Patented June 3, 1919.

Application filed September 13, 1918. Serial No. 254,024.

. This invention relates to spark plugs, for

ignition purposes in internal combustion engines, and has for its objectthe provision of a spark plug having a procelain insulating portionmolded within the shell of the plug and about internal projections onthe shell whereby the porcelain portion will be a permanent part of andbe inseparable from the shell to prevent any possible displacement, theporcelain, being also molded about the central contact wire which isfurthermore provided with a retaining flange.

A very important object is the provision of a spark plug of thischaracter in which the firing points are disposed at a considerabledistance beyond the end of the plug and spaced an unusually longdistance apart whereby a very long hot spark may be produced, longerthan in the commonly used plugs, to insure explosion of a charge, thethickness and special construction of the porcelain core preventingshort circuiting within the plug even though the firing points becomefouled.

Another object is the provision of a spark plug of this character whichwill be extremely simple and inexpensive in manufacture, efficient anddurable in use, and a general improvement in the art.

lVith the above and other objects and advantages in view, the inventionconsists in the details of construction to be hereinafter more fullydescribed and claimed, and illustrated in the accompanying drawings inwhich t Figure 1 is a side elevation of a plug constructed in accordancewith my invention,

Fig. 2 is a longitudinal sectional view therethrough and Fig. 3 is across sectional view.

Referring more particularly tothe drawing the numeral 5 designates theshell or body portion of the plug which is formed angular in crosssection as shown and which has one end reduced and externally threadedfor engagement within the usual opening in an engine cylinder, as shownat 6. Extending inwardly from theinner wall of the body portion 5 areprojections 7 adapted to serve as retaining means for the porcelain core8 which is molded directly within the body 6 and which has both endsextending beyond the ends of the body 5 as shown at 9 and 10. Theprojecting end 10 is formed convex as shown.

. Disposed centrally of and molded Within the porcelain core 8 is acontact member 11 in the form of a wire which is provided with anoutwardly extending circumferential flange 12 which will prevent anydisplacement of )the contact member 11 in respect to the core 8. At itsother end, the contact member 11 is threaded as shown at 13 and hasthreaded thereon a locking nut ll which bears against the end 9 of thecore for holding the contact member 11 firmly in position. It will benoted that the other end of the contact member 11 extends an appreciabledistance beyond the convex end 10 of the core so as to extend anappreciable distance into the firing chamber of an engine cylinder.

The other contact member, that is the ground connection member, extendsfrom the threaded end 6 of the shell or body 5 and is designated by thenumeral 15. .At its extremity the contact member 15 is provided with alaterally offset portion 16 directed toward and in alinement with theend of the contact member 11. The distance between the end of thelaterally ofi'set portion 16 of the contact member 15 and the contactmember 11 is several times the distance between the contact points ofthe ordinary form of spark plug whereby an extremely long hot spark maybe obtained. Owing to the peculiar construction of the plug which is soformed that the central contact member 11 is comparatively remote fromthe 'outer shell 5, there will be practically no danger of shortcircuiting within the core even though the contact members 11 and 16should become fouled. Furthermore, in View of the fact that the core ismolded directly into the shell, there will be no space between the coreand the shell for the accumulation of soot, which would result infouling of the plug and resultant short circuiting with the core.

From the foregoing description and a study of the drawing it will beapparent that I have thus provided a very simplyconstructed spark plugby means of which an unusually long and hot spark may be produced and inwhich the danger of short circuiting Within the body of the plug will bereduced to the minimum.

Having thus described my invention I claim A spark plug comprising anouter shell provided at one end with a threaded portion, a plurality ofspaced inwardly extending projections formed on the inner periphery ofsaid shell and arranged in circumferential series, an insulating core ofporcelain molded within said body and engaging, the entire internalperiphery thereof and having both ends extending beyond the ends of thebody, the end projecting beyond the threaded end of said shell being asection of a sphere, a contact member extending centrally of andembedded Within said core and having its active end extendin anappreciable distance beyond the partlally spherical end of said core, aretaining flange formed on said central contact member intermediate itsends whereby longitudinal displacement thereof Will be prevented, and acontact member extending from said shell and having a laterally directedend extending toward the side of said first named contact memberadjacent its end.

In testimony whereof I affix my signature.

LAROY C. MONISMITH.

